I've known my BF's daughter since she was 10, she's now 13 and here for the summer. This is the first time that she and I have really hung out by ourselves. It is so cool. We went to the movies the other day, then to the mall one day (where she helped me pick out bathing suits.) Then today her dad is going to a charity golf tournament so he just called and said she wanted to know what I was doing.
In the past she would just go to her aunt's or grandmother's, but now she wants to hang out with me.
And last night we were all playing cards and she got mad at one of the rules so she said "I'm going upstairs with [my sister's name] and never speaking to you again." I took that as a really good sign that she feels safe enough to say that to me. And of course she spoke to me again.